104 lines
8.5 KiB
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104 lines
8.5 KiB
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<!-- Common Lisp HyperSpec (TM), version 7.0 generated by Kent M. Pitman on Mon, 11-Apr-2005 2:31am EDT -->
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<TITLE>CLHS: Function SUBLIS, NSUBLIS</TITLE>
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<H1><A REV=MADE HREF="http://www.lispworks.com/"><IMG WIDTH=80 HEIGHT=65 ALT="[LISPWORKS]" SRC="../Graphics/LWSmall.gif" ALIGN=Bottom></A><A REL=TOP HREF="../Front/index.htm"><IMG WIDTH=237 HEIGHT=65 ALT="[Common Lisp HyperSpec (TM)]" SRC="../Graphics/CLHS_Sm.gif" ALIGN=Bottom></A> <A REL=PREV HREF="f_cp_tre.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Previous]" SRC="../Graphics/Prev.gif" ALIGN=Bottom></A><A REL=UP HREF="c_conses.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Up]" SRC="../Graphics/Up.gif" ALIGN=Bottom></A><A REL=NEXT HREF="f_substc.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Next]" SRC="../Graphics/Next.gif" ALIGN=Bottom></A></H1>
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<A NAME="sublis"><A NAME="nsublis"><I>Function</I> <B>SUBLIS, NSUBLIS</B></A></A> <P>
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<P><B>Syntax:</B><P>
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<P>
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<B>sublis</B> <I>alist tree <TT>&key</TT> key test test-not</I> => <I>new-tree</I><P>
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<B>nsublis</B> <I>alist tree <TT>&key</TT> key test test-not</I> => <I>new-tree</I><P>
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<P>
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<P><B>Arguments and Values:</B><P>
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<P>
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<I>alist</I>---an <A REL=DEFINITION HREF="26_glo_a.htm#association_list"><I>association list</I></A>. <P>
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<I>tree</I>---a <A REL=DEFINITION HREF="26_glo_t.htm#tree"><I>tree</I></A>. <P>
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<I>test</I>---a <A REL=DEFINITION HREF="26_glo_d.htm#designator"><I>designator</I></A> for a <A REL=DEFINITION HREF="26_glo_f.htm#function"><I>function</I></A> of two <A REL=DEFINITION HREF="26_glo_a.htm#argument"><I>arguments</I></A> that returns a <A REL=DEFINITION HREF="26_glo_g.htm#generalized_boolean"><I>generalized boolean</I></A>. <P>
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<I>test-not</I>---a <A REL=DEFINITION HREF="26_glo_d.htm#designator"><I>designator</I></A> for a <A REL=DEFINITION HREF="26_glo_f.htm#function"><I>function</I></A> of two <A REL=DEFINITION HREF="26_glo_a.htm#argument"><I>arguments</I></A> that returns a <A REL=DEFINITION HREF="26_glo_g.htm#generalized_boolean"><I>generalized boolean</I></A>. <P>
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<I>key</I>---a <A REL=DEFINITION HREF="26_glo_d.htm#designator"><I>designator</I></A> for a <A REL=DEFINITION HREF="26_glo_f.htm#function"><I>function</I></A> of one argument, or <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A>. <P>
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<I>new-tree</I>---a <A REL=DEFINITION HREF="26_glo_t.htm#tree"><I>tree</I></A>. <P>
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<P><B>Description:</B><P>
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<P>
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<A REL=DEFINITION HREF="#sublis"><B>sublis</B></A> makes substitutions for <A REL=DEFINITION HREF="26_glo_o.htm#object"><I>objects</I></A> in <I>tree</I> (a structure of <A REL=DEFINITION HREF="26_glo_c.htm#cons"><I>conses</I></A>). <A REL=DEFINITION HREF="#nsublis"><B>nsublis</B></A> is like <A REL=DEFINITION HREF="#sublis"><B>sublis</B></A> but destructively modifies the relevant parts of the <I>tree</I>. <P>
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<A REL=DEFINITION HREF="#sublis"><B>sublis</B></A> looks at all subtrees and leaves of <I>tree</I>; if a subtree or leaf appears as a key in <I>alist</I> (that is, the key and the subtree or leaf <A REL=DEFINITION HREF="26_glo_s.htm#satisfy_the_test"><I>satisfy the test</I></A>), it is replaced by the <A REL=DEFINITION HREF="26_glo_o.htm#object"><I>object</I></A> with which that key is associated. This operation is non-destructive. In effect, <A REL=DEFINITION HREF="#sublis"><B>sublis</B></A> can perform several <A REL=DEFINITION HREF="f_substc.htm#subst"><B>subst</B></A> operations simultaneously. <P>
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If <A REL=DEFINITION HREF="#sublis"><B>sublis</B></A> succeeds, a new copy of <I>tree</I> is returned in which each occurrence of such a subtree or leaf is replaced by the <A REL=DEFINITION HREF="26_glo_o.htm#object"><I>object</I></A> with which it is associated. If no changes are made, the original tree is returned. The original <I>tree</I> is left unchanged, but the result tree may share cells with it. <P>
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<A REL=DEFINITION HREF="#nsublis"><B>nsublis</B></A> is permitted to modify <I>tree</I> but otherwise returns the same values as <A REL=DEFINITION HREF="#sublis"><B>sublis</B></A>. <P>
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<P><B>Examples:</B><P>
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<P>
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<PRE>
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(sublis '((x . 100) (z . zprime))
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'(plus x (minus g z x p) 4 . x))
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=> (PLUS 100 (MINUS G ZPRIME 100 P) 4 . 100)
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(sublis '(((+ x y) . (- x y)) ((- x y) . (+ x y)))
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'(* (/ (+ x y) (+ x p)) (- x y))
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:test #'equal)
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=> (* (/ (- X Y) (+ X P)) (+ X Y))
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(setq tree1 '(1 (1 2) ((1 2 3)) (((1 2 3 4)))))
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=> (1 (1 2) ((1 2 3)) (((1 2 3 4))))
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(sublis '((3 . "three")) tree1)
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=> (1 (1 2) ((1 2 "three")) (((1 2 "three" 4))))
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(sublis '((t . "string"))
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(sublis '((1 . "") (4 . 44)) tree1)
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:key #'stringp)
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=> ("string" ("string" 2) (("string" 2 3)) ((("string" 2 3 44))))
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tree1 => (1 (1 2) ((1 2 3)) (((1 2 3 4))))
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(setq tree2 '("one" ("one" "two") (("one" "Two" "three"))))
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=> ("one" ("one" "two") (("one" "Two" "three")))
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(sublis '(("two" . 2)) tree2)
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=> ("one" ("one" "two") (("one" "Two" "three")))
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tree2 => ("one" ("one" "two") (("one" "Two" "three")))
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(sublis '(("two" . 2)) tree2 :test 'equal)
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=> ("one" ("one" 2) (("one" "Two" "three")))
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(nsublis '((t . 'temp))
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tree1
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:key #'(lambda (x) (or (atom x) (< (list-length x) 3))))
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=> ((QUOTE TEMP) (QUOTE TEMP) QUOTE TEMP)
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</PRE>
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</TT> <P>
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<P><B>Side Effects:</B><P>
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<P>
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<A REL=DEFINITION HREF="#nsublis"><B>nsublis</B></A> modifies <I>tree</I>. <P>
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<P><B>Affected By:</B> None.
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<P>
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<P><B>Exceptional Situations:</B> None.
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<P>
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<P><B>See Also:</B><P>
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<P>
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<A REL=DEFINITION HREF="f_substc.htm#subst"><B>subst</B></A>, <A REL=CHILD HREF="03_ba.htm">Section 3.2.1 (Compiler Terminology)</A>, <A REL=CHILD HREF="03_f.htm">Section 3.6 (Traversal Rules and Side Effects)</A> <P>
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<P><B>Notes:</B><P>
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<P>
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The <TT>:test-not</TT> parameter is deprecated. <P>
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Because the side-effecting variants (e.g., <A REL=DEFINITION HREF="#nsublis"><B>nsublis</B></A>) potentially change the path that is being traversed, their effects in the presence of shared or circular structure structure may vary in surprising ways when compared to their non-side-effecting alternatives. To see this, consider the following side-effect behavior, which might be exhibited by some implementations: <P>
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<PRE>
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(defun test-it (fn)
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(let* ((shared-piece (list 'a 'b))
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(data (list shared-piece shared-piece)))
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(funcall fn '((a . b) (b . a)) data)))
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(test-it #'sublis) => ((B A) (B A))
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(test-it #'nsublis) => ((A B) (A B))
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</PRE>
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</TT> <P>
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<P><HR>The following <A REL=META HREF="../Front/X3J13Iss.htm">X3J13 cleanup issues</A>, <I>not part of the specification</I>, apply to this section:<P><UL><LI> <A REL=CHILD HREF="../Issues/iss345.htm">TEST-NOT-IF-NOT:FLUSH-ALL</A><LI> <A REL=CHILD HREF="../Issues/iss240.htm">MAPPING-DESTRUCTIVE-INTERACTION:EXPLICITLY-VAGUE</A><LI> <A REL=CHILD HREF="../Issues/iss083.htm">CONSTANT-MODIFICATION:DISALLOW</A><LI> <A REL=CHILD HREF="../Issues/iss138.htm">DOTTED-LIST-ARGUMENTS:CLARIFY</A><P></UL><HR>
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